A known apparatus for the purpose comprises a perforated plate and a multi-vaned or bladed rotary cutting tool which is mounted in front of, that is to say, downstream of the plate. The cutting tool comprises a cutter holder and cutter blades, the tool being surrounded by a particle granulation chamber which, in use, has a coolant liquid flowing therethrough.
In a further known granulation apparatus, the cut granulated materials or granules are centrifuged in a film of water, which film is produced by means of a pressureless overflow on a vertically disposed internal wall of the granulation chamber. The chamber may be in the form of a collector housing.
The cut granules are subjected to high, centrifugal forces by the cutters which rotate at a high speed. They therefore strike against the wall of the housing and are reflected to the centre of the housing. Due to the high speed impact of the granules with the film of water and the housing wall located therebehind, the granulates are liable to be deformed, which deformation may impair their friability.
If the chamber or housing for collecting the granules has an encircling internal wall which is inclined both downwardly and outwardly, the angle of reflection of the cut granulates is increased. This greatly reduces the risk of their deformation upon impact with the water or the wall. On the other hand, it is very difficult to produce a film of water of a uniform thickness and which can quickly transport away the cut granules on such an inclined surface.